Wireless networks have evolved from systems having a single antenna to systems having a limited number of multiple antennas (e.g., 2 or 4) supporting multiple input, multiple output (MIMO) communications. These systems may be referred to as legacy LTE systems. Recently, wireless networks have evolved to include base stations with a large number of antenna elements (often 100 or more). These systems are referred to as massive MIMO (M-MIMO) systems. It is possible that the users are also equipped with a large number of antenna elements.
M-MIMO systems provide benefits such as increased bandwidth and increased downlink beamformed gain. However, M-MIMO utilizes different pilot structures and procedures for channel estimation than legacy LTE systems. As networks evolve, the ability for M-MIMO and legacy LTE to coexist and interwork efficiently is crucial.
The disclosure will now be described with reference to the accompanying drawings. In the drawings, like reference numbers generally indicate identical, functionally similar, and/or structurally similar elements. The drawing in which an element first appears is indicated by the leftmost digit(s) in the reference number.